It can be tempting to think that when one member of a husband-wife couple marries again that the other spouse has died or that there was a divorce. That’s not always the case.
Sometimes couples just separated with no legal arrangements at all. One of them may have up and left or they may have decided to just part company without worrying about legal entanglements. An ancestral couple of mine did just that in New York State in the early 19th century and both of them married again and had children with subsequent spouses. No divorce can be located.
Another ancestor of mine, Clark Sargent, is supposed to have died near Rockford, Illinois, in the 1840s, a year or so before his wife married her second husband. It’s too early for a death record. Despite him owning farmland and having small children, there was no estate settlement or guardianship for his children. His daughter in her Civil War widow’s pension application even suggests that her father might have simply “run off” instead of dying–she also refers to him as a gadabout.
When divorces were more difficult to get and it was easier to move and start a new life, that might be what your relative did.
Don’t assume thought that is what happened. Make certain you have looked into all extant court, property, and other records in the area where the person lived. There may be something that mentions the couple’s separation–like the deed between a relative and his wife in Kentucky in the 1860s that separated their property but stated that they were not technically divorced.